Hibernate HQL示例七:查询过滤器的使用

查询过滤器指的是:配置好后,会在该对象上的每一条查询语句上自动加上查询条件:

如:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.bjsxt.hibernate.Student" table="t_student">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
		<property name="createTime"/>
		<many-to-one name="classes" column="classid"/>
		<filter name="idfilter" condition="id &lt; :myid"/>
	</class>
	<query name="searchStudents"><![CDATA[
		select s from Student s where s.id < ?
	]]>
	</query>
	<filter-def name="idfilter">
		<filter-param name="myid" type="integer"/>
	</filter-def>
</hibernate-mapping>

 

package com.bjsxt.hibernate;

import java.util.Iterator;
import java.util.List;

import org.hibernate.Session;

import junit.framework.TestCase;

/**
 * 查询过滤器测试
 * @author Administrator
 *
 */
public class FilterQueryTest extends TestCase {
	
	public void testQuery1() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			
			session.enableFilter("idfilter")
			       .setParameter("myid", 10);
			
			List students = session.createQuery("from Student")
			.list();
			
			for (Iterator iter = students.iterator();iter.hasNext();) {
				
				Student student = (Student)iter.next();
				System.out.println(student.getName());
			}
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}	
	}
	
}

 

上述代码中只有from Student但执行的时候发出的语句是:

Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.createTime as createTime1_, student0_.classid as classid1_ from t_student student0_ where student0_.id < ?

 

过滤器在配置文件中的使用:

<filter name="idfilter" condition="id &lt; :myid"/>

 

	<filter-def name="idfilter">
		<filter-param name="myid" type="integer"/>
	</filter-def>